Tom Gjelten

The Pilgrims are among the early heroes of American history, celebrated every Thanksgiving for their perseverance in the New World against great odds.

To Christian conservatives, they are role models for another reason as well: They were deeply committed to their Christian faith and not afraid to say so.

In the Mayflower Compact, the governing document signed shortly before the Pilgrims disembarked in Massachusetts' Provincetown Harbor, Pilgrim leaders said they undertook their voyage across the Atlantic "for the glory of God and the advancement of the Christian faith."

Religion is apparently weakening in America. A new report from the Pew Research Center shows that the percentage of Americans who say they believe in God, pray daily and attend church regularly is declining.

Among the findings:

The share of Americans who say they are "absolutely certain" that God exists has dropped 8 percentage points, from 71 percent to 63 percent, since 2007, when the last comparable study was made.

Pope Francis arrives in Washington, D.C., this afternoon for his first trip to the U.S. Here's a look at some of the key moments to watch during the leader of the Roman Catholic Church's six-day visit.

Nearly a century ago, immigrants from Germany and Ireland founded St. Helena Church in a working-class neighborhood in north Philadelphia.

Immigrants, and their children, still fill the pews at St. Helena's — but the vast majority of them are now from Vietnam, Latin America, the Philippines and Africa. Weekly masses are conducted in Spanish and Vietnamese as well as English. The senior priest, the Rev. Joseph Trinh, is himself a Vietnamese refugee. One of his associate priests is from Haiti, and another is from Ecuador.

Many ministers do their best to stay away from politics when they preach, but hundreds of conservative pastors around the country are so upset about what they see as a moral crisis in government that they are preparing to run for public office themselves, with the goal of bringing "biblical values" to the political arena.

The initiative is led by David Lane, a born-again Christian and self-described "political operative" who has organized four large-scale training sessions in which evangelical pastors are tutored in the practical aspects of running a political campaign.

As a 12-year-old Catholic boy growing up in England, Michael Fitzgerald decided he wanted to be a missionary in Africa. Eight years later, he was studying theology and learning Arabic in Tunisia.

He went on to devote his priestly ministry to the promotion of interfaith understanding between Muslims and Christians, and became one of the top Roman Catholic experts on Islam. He has served as the archbishop of Tunisia, the papal nuncio — effectively a Vatican ambassador — in Cairo, and the Vatican's delegate to the Arab League.

This week, a man was sentenced to die in Saudi Arabia because he renounced his faith in Islam; a Hindu leader in India made a new accusation against Mother Teresa; a mosque near Bethlehem was set on fire.

The reluctance of President Obama and others to link Middle East terrorism explicitly to Islam at this week's "Countering Violent Extremism" summit exposed them to withering criticism, and not entirely from conservatives. Some Muslim reformers who have been struggling to combat radicalism in their mosques and communities have been willing to talk about the extremist ideologies they encounter.

Outrage over the murder of three young Muslim Americans in North Carolina last week has gone international. The Organization of Islamic Cooperation said Saturday that the killings reflected "Islamophobia" and "bear the symptoms of a hate crime," but local authorities say they don't yet know what motivated the murders.

The man held responsible for the killings is an avowed atheist. Whether that's relevant in this case is not clear, but some experts see a new extremism developing among some atheists.

The nuclear deal between Iran and six world powers will face its first test this weekend. Inspectors from the International Atomic Energy Agency are due to make a long-delayed visit to a nuclear site in Iran where plutonium could be produced.

A nuclear reactor and associated production plant in Arak are a special concern because plutonium can be used in a nuclear bomb. Under last month's accord, Iran promised to allow inspections of its nuclear facilities.

Officials on both sides say they are committed to the nuclear deal, but keeping it on track will be a challenge.

Along with the privacy advocates and the national security establishment, there is another set of players with strong views on NSA surveillance programs: U.S. tech companies.

Google and five other companies weighed in on the surveillance debate last month, sending a letter to members of the Senate Judiciary Committee, supporting legislation to reform National Security Agency surveillance programs.

The controversy over the National Security Agency's surveillance programs has exposed a problem in the oversight of those programs: The development of the relevant technology has outpaced the laws and policies that govern its use.

Recent disclosures about NSA surveillance have affected U.S. relations with allies and tainted America's image around the world. Now the fallout seems to be creeping into the U.S. tech sector.

Cisco Systems, which manufactures network equipment, posted disappointing first-quarter numbers this week and warned that revenues for the current quarter could drop as much as 10 percent from a year ago — partly as a consequence of the NSA revelations.